In some of the other threads, Mistress Woods has spoken of various humiliations or humiliation rituals including toilet or full toilet.

If a guy has asked for full toilet, then, how is it humiliating for him to receive what he has requested? Or, do some mistresses make things worse than expected so as to make things humiliating? Or, do some guys ask for humiliation? Or, do you who are mistresses bend the session to that it becomes badly humiliating, even if a guy was not expecting humiliation?

How does humiliation fit with the yukky "punishment" when the punishment is expected or requested? What about those instances in which it is not considered by the sub to be a punishment or bad?

First and foremost, session activities need to be consensual. That said “humiliation” and “forced” are similar. I think they are both used to imply someone wants to push things (within reason). With regards to FT, taking a dump on the sub would qualify, but what if she then rubbed it all over his face? That might qualify as humiliation.

In reality they are both words that mean “I want to partake in activity that ‘normal’ people would consider crazy”. One activity I can’t get enough of in a session is being spit on (or in my mouth); something that out in public would be truly humiliating .

They’re both code words, but instead of asking for either of those it is better to come right out and tell her what you are looking for (ironically, for some that could be humiliating).

Three ways that the humiliation still comes through. One way is that the sub 'forgets' about the fact that the Mistress is doing what he asked her to do. I think this is a very common aspect and practice in BDSM paid sessioning.

Two is that the Mistress laughs at the very real fact that you want her to shit on you and even paid her to do so. I think many would consider her words to be humiliating.

Third, and I believe that you alluded to this, is that she creatively adds on to your request. For me, a memorable session involved the Mistress having me lie there, covered in her feces, while she carefully freshened up herself, in no particular hurry.

Then she had me get up, still streaked with her waste, and I was made to wipe her ass spotlessly cleaned, being reminded how important it was that her ass be spotless. Never mind that I still had her shit on my face and wasn't allowed to do anything about it.

The humiliation is always there, in the background, trust me.
There are very few Dommes (Unicorns) that can reconcile that image with anyone with anyone they wish to spend vanilla time with.